1. Field of the Invention
The subject invention relates to methods and apparatus for guiding an advancing tape and, for instance, has utility in magnetic tape transporst, photographic film handling apparatus and other tape and web transporting or handling equipment wherein a precision guidance of a tape, film or other web is required.
2. Disclosure Statement
The following disclosure statement is made pursuant to the duty of disclosure imposed by law and formulated in 37 CFR 1.56(a). No representation is hereby made that information thus disclosed in fact constitutes prior art, inasmuch as 37 CFR 1.56(a) relies on a materiality concept which depends on uncertain and inevitably subjective elements of substantial likelihood and reasonableness and inasmuch as a growing attitude appears to require citation of material which might lead to a discovery of pertinent material though not necessarily being of itself pertinent. Also, the following comments contain conclusions and observations which have only been drawn or become apparent after conception of the subject invention or which contrast the subject invention or its merits against the background of developments which may be subsequent in time or priority.
Various tape guides and similar devices with tiltable members have become known. For instance, U.S. Pat. No. 3,140,033, by J. C. Zivny, issued July 7, 1964 shows a tape tension equalizer with tiltable guide member. U.S. Pat. No. 3,608,796, by J. E. Morse et al, issued Sept. 28, 1971 shows a web-supporting roller rotatably mounted on a longitudinal shaft and pivotally movable about a gimbal axis relative to such shaft to compensate for misalignment of the advancing web, and U.S. Pat. No. 3,658,227, by J. F. Stephens, issued Apr. 25, 1972 for a tape guide spindle having an inner sleeve fixed in position on a shaft and an outer sleeve held in spaced relationship to the inner sleeve by an O-ring of resilient material permitting the outer sleeve to tilt for accommodating tape approaching the outer sleeve out of proper alignment. In all these prior proposals, the pivot axis or fulcrum is located midway of the tape guide, whereby the guiding function proceeds somewhat arbitrarily without strict reference to a laterally exact position of tape travel.
Against that background, a more advanced proposal is apparent from the subject assignee's U.S. Pat. No. 4,091,979, by L. B. Browder, issued May 30, 1978 for methods and apparatus for precision guiding a web; special reference being made to FIGS. 2 and 3 thereof, showing a system for precision guiding a web against a reference surface spaced from the tiltable tape guide member. While claims in that patent are generic to the improvement disclosed therein, as well as to the invention herein disclosed, the subject invention constitutes a substantial advance over that prior system, which provided web guidance in only one direction of web travel, while arresting such guidance for reverse web travel.
In the course of a novelty search based on the subject disclosure, several patents were found, none of which, however, presented a solution to the problems expressed or implicit herein, as may be seen from the following.
U.S. Pat. No. 1,834,914, by G. R. Goff, issued Dec. 1, 1931, discloses a bobbin clutching spindle and clutched bobbin having circumferential rings around a lower portion of the periphery thereof. U.S. Pat. No. 3,015,932, by H. W. McCard, issued Jan. 9, 1962 discloses a twister head for textiles having O-rings around outer races of two bearings for elastomeric suspension. U.S. Pat. No. 3,035,402, by A. Westall et al, issued May 22, 1962 discloses textile spinning spindles with spaced journal and footstep bearings. U.S. Pat. No. 3,285,610 by G. B. Shields, issued Nov. 15, 1966 discloses a magnetic recorder cartridge lockdown mechanism in which a pinch roller is mounted on a shaft having an annular, spherical protrusion permitting wobbling self-adjustment of the pinch roller in alignment with a capstan shaft. U.S. Pat. No. 3,315,859, by W. S. Owen et al, issued Apr. 25, 1967 discloses a web tracking mechanism having a web guide roller pivotally supported on a shaft by means of a spherical inner race located on the shaft and a pair of annular outer races interposed between such inner race and the inner periphery of the roller. U.S. Pat. No. 3,414,339, by R. B. Hay, issued Dec. 3, 1968 discloses an oil-free bearing assembly in which O-rings are squashed between a bearing sleeve and bearing housing to form a friction fitting.
U.S. Pat. No. 3,588,204, by V. V. Abashkin et al, issued June 28, 1971 discloses an axle-box for rolling stock employing a pair of roller bearings. U.S. Pat. No. 3,662,937, by M. P. Borman, issued May 16, 1972 discloses a magnetic tape cartridge having self-aligning tape guide and pressure rollers supported on generally spherical steel balls mounted on a shaft, and complementary outer races extending to the inner wall of the tape guide or pressure roller. U.S. Pat. No. 3,788,437, by J. W. A. Camp, issued Jan. 29, 1974 discloses a self-centering clutch release bearing assembly supported for limited radial movement and spring-biased into engagement with a bearing carrier. U.S. Pat. No. 3,854,646, by Dorfel et al, issued Dec. 17, 1974 discloses a pressure-balanced guide roller assembly employing multiple bearing units. U.S. Pat. No. 3,949,919, by Y. Takei, issued Apr. 13, 1976 discloses a capstan assembly with spaced self-aligning capstan bearings, each having an outer convex surface received in corresponding retainers. U.S. Pat. No. 4,148,464, by E. Fog et al, issued Apr. 10, 1979 discloses a hydraulic motor fastened within a pulley with the aid of elastomeric seals and a bearing associated therewith.
Another tape guide roller employed primarily at helical video tape scanners employed a single no-preload ball bearing between a post and the inner surface of a hollow-cylindrical tape guide member having a tape guide surface located circumferentially at one end of the rotating tape guide member. The roller bearing is laterally offset in a direction away from the tape guide surface from a central location corresponding to a longitudinal center line of the advancing tape.
Accordingly, the advancing tape is guided into and in engagement with the tape guide surface under the influence of a tilting motion of the tape guide member due to the presence and operation of the mentioned ball bearing. At high tape speeds the performance of that type of tape guide deteriorated in running characteristics and smoothness and the mentioned single-bearing principle did not prove suitable for high-speed operation.